Fixed integration edit page not showing after creating new integration
Fixed integration edit page not showing after creating new integration

refs https://github.com/TryGhost/Admin/commit/4cbb56a0df879e0e0a6e7ba4a9e31697b22d8f5e

- `beforeClose` behaviour has changed slightly with the upgraded ember-promise-modals
- added a guard for the modal existing when transitioning back to the integrations index screen, this makes sure we're not transitioning back to the index screen after the modal has already initiated a transition to the integration edit screen

TryGhost/Ghost-Admin,TryGhost/Ghost-Admin